Submit only checks 400 when printing success (404 etc. unhandled)

[jdsutherland]

Currently, submit only checks for 400 responses before printing a success message. 404s are silent and the resulting output misleadingly indicates that the submission was successful.

Mentioned in #770 (comment).

[iHiD]

Hello @exercism/cli :)

This has come up a couple of times recently. It's been suggested that this commit never got released. If that's so, could we release it? Is there anything else blocking that?

Thanks :)

[kytrinyx]

I'll do a release to day!

[iHiD]

(cc @NobbZ)